A drive axle of a vehicle comprising an electric motor, a differential gear unit and a planetary gear unit is described in DE102004026039A1. The electric motor can be brought into a drive connection with the differential gear unit by means of a coupling apparatus which is operatively connected to the planetary gear unit. The planetary gear unit comprises an input-side sun gear which is connected to a drive shaft of the electric motor, a ring gear, and planetary gears which are disposed radially between the sun gear and the ring gear, mounted on a planet carrier and engaged with the sun gear and an inner tooth system of the ring gear, the planet carrier being coupled to the differential gear unit and it being possible, by means of the coupling apparatus, to fix or release the ring gear relative to a component which is fixed to the housing. When the ring gear is stationary in relation to the component which is fixed to the housing, the differential gear unit and thus the vehicle are driven, the rotational speed of the electric motor being reduced by the reduction gear unit. If the ring gear is released, the rotating drive shaft of the electric motor sets the ring gear in rotation and the differential gear unit and thus the vehicle are not driven. Thus, only one gear ratio is available for driving the vehicle. It is also disadvantageous that this device requires a lot of space owing to the arrangement of the electric motor, the planetary gear unit and the differential gear unit in series in the axial direction, and thus is not very compact.